Grinding wheel dressing means in saw sharpening apparatus



L. J. NIELSEN May 30, 1961 GRINDING WHEEL DRESSING MEANS IN SAWSHARPENING APPARATUS Filed April 28, 1958 IN V EN TOR.

Leo cZNieJSen A-H s.

United States Patent C GRINDING WHEEL DRESSING MEANS IN SAW SHARPENINGAPPARATUS Leo J. Nielsen, Rosebnrg, Oreg.

(P.0. Box 3576, Eugene, Oreg.)

Filed Apr. 28, 1958, Ser. No. 731,397

3 Claims. (CI. 76-37) This invention relates to sharpening apparatus,and more particularly to saw chain sharpening apparatus having agrinding wheel, and dresser means or mechanism for dressing the grindingwheel to take care of wear occurring during use.

Generally it is an object of this invention to provide for a grindingwheel improved dresser mechanism which enables dressing of thecircumferential edge of a grinding wheel to a true and accurate radius,and which may be readily set up without complex adjustment.

Another object of the invention is to provide improved sharpeningapparatus comprising a frame and a swingable grinding wheel mount, whichalso comprises dressing mechanism carried on the grinding wheel mountwhich rapidly and accurately may be set up to dress the peripheral edgeof a grinding wheel, and which requires little readjustment tocompensate for changes in the diameter of a grinding Wheel. The dressingmechanism, when not in use, is easily swung to a position out of the wayof the grinding wheel.

When sharpening the teeth of a saw chain with a grinding wheel, thewheel is lowered against a tooth with one face and the circumferentialedge of the wheel abradingaway the steel of the tooth. In such anoperation, the shape of the edge and face of the grinding wheeldetermines the shape of the sharpened tooth. Thus it is important thatthe circumferential edge of the grinding wheel be dressed offoccasionally as it wears away. In the usual instance, the edge of thewheel is dressed oif so that it curves from one wheel face to the otherover a radius corresponding to about one-half the thickness of thewheel. When so dressed the side faces of the wheel meet in approximatetangential relationship the convexly curving edge extending between andjoining the opposite faces of the wheel. 7

Usually grinding wheels are dressed by hand. It is diflicult with handdressing to obtain a true round at the edge of a wheel. Dressermechanisms held by support means against the edge of a wheel are alsoknown, however, mechanisms known to date have required a considerablenumber of adjustments to set them up properly, and have also had thedisadvantage that most of these adjustments have had to be made eachtime it is desired to dress a wheel to its then attained diameter.

This invention contemplates a construction wherein a dressing or cuttingelement, ordinarily a diamond point, is carried adjacent the edge of agrinding wheel by means of a supporting arm or member mounted forpivotal movement about an axis extending in a direction substantiallyparallel to the axis of rotation of the grinding wheel. Means areprovided also for rotating the supporting arm about an axis which isperpendicular to the axis of rotation of the wheel, the rotation axisfor the supporting arm being referred to herein as an adjustment axis.This supporting arm or member has an oifset portion at one end adjacentthe grinding wheel, and this offset portion carries the diamond point.The diamond point is adjustable in a direction extending radially 'iceof the rotational axis for the supporting member, i.e., radially of theaforementioned adjustment axis.

Once the diamond point is positioned on the offset portion, the cuttingsweep of the diamond point, which is determined by the degree of offsetof the diamond from the adjustment axis for the supporting member, isfixed. The support member may then be pivoted about its pivot axis withthe diamond point riding radially toward or away from the edge of awheel, without effecting the cutting sweep of the diamond point. Theorganization has the advantage of permitting the dressing of the wheelwith progressive infeeding of the diamond point as the diameter of thegrinding wheel diminishes with continued dressing and wear.

Another object of the invention is to provide a grindequal amount oneither side of a plane extending through the median plane of the Wheelparallel to the wheel faces. This requires that the supporting armrotate about an adjustment axis lying in this plane. With substitutionof a grinding wheel of a dilferent thickness, the location of thiscentral plane changes. The construction of this invention accommodateslateral shifting of the adjustment axis of the supporting member to takecare of this change. The adjustment axis may also be shifted should itbe desired to impart to the edge of a wheel a round curved about acenter located closer to one face of the wheel than the other.

Other objects, novel features and advantages are present in theinvention, which is described hereinbelow in conjunction with theaccompanying drawings wherein:

Fig. 1 is a perspective view of saw sharpening apparatus constructedaccording to this invention, the apparatus including a frame and apivoted grinding wheel mount carried over the frame;

Fig. 2 is a section view, slightly enlarged, along the line 22 in Fig.1, illustrating details of the mounting for one end of the grindingwheel mount;

Fig. 3 is a section view, also enlarged, along the line 3-3 in Fig. 1,showing the supporting arm of the invention and the mounting of the armon the grinding wheel mount;

Fig. 4 is a section view along the line 4-4 in Fig. 3; and

Fig. 5 is a section view along the line 55 in Fig. 3.

Referring now to the drawings for a description of an embodiment of theinvention, and in particular to Fig. l, 10 indicates the sharpeningapparatus generally. The apparatus comprises a base frame 11 shaped as apyramidal frustrum, gripping means 12 along the forward top edge of thebase frame for clamping onto a saw chain 14 during sharpening, and apivotally mounted grinder wheel mount 13. When sharpening a saw toothwith the device, the free or nonpivoted end of grinding wheel mount 13is pivoted downwardly toward gripping means 12 and any saw chain 14clamped therein.

Specifically, base frame 11 has end walls 16 and side walls 17 joinedtogether at their end edges and supporting along their top edges ahorizontally disposed table surface 18. Gripping or clamping means 12 issecured to the front face of front side wall 17, and comprises a rearclamp member 20 and a front clamp member 21, which may be strips ofsteel. The rear clamp member is adjacent the side wall, and the frontclamp member is spaced a small distance outwardly from the rear clampmember and held in place by screws 22 at each of its ends.

Front clamp member 21 bows intermediate its ends, and is flexible andresilient. Extending through the center Patented May 30, 1961 3 of thefront and rear clamp members, near their base edges, is a rotatable pin23 fixed in side wall 17 against axial movement. Pivoted to the outerend of pin 23 is a swingable cam handle 24. The cam handle is pivota'bleabout an axis extending transversely of pin 23. The cam handle has apair of earns 25 integral with the handle which move in against frontclamp member 21 when the handle is pivoted about this axis. Cam handle24 and cams 25 constitute a means tightly for securing a saw chainbetween clamp members 20, 21.

Secured to front side wall 17 and extending inwardly from its rear faceis a pin 36. Rotatably mounted on pin 36 is a brace arm 37. The bracearm pivotally carries at its upper end an indexing finger 38, whichdepends downwardly from the brace arm with the lower end thereof overclamp members 20, 21.

Extending from an intermediate portion of brace arm 37 outwardly throughone of the end walls 16 is an adjustor rod 39. Rod 39 has a threadedportion 40 received in an internally threaded bore provided in baseframe 11. Turning of the adjustor rod operates either to advance or toretract the rod longitudinally of the base frame. The inner end of therod abuts brace arm 37. If the rod is moved inwardly, the brace arm ismoved in a counterclockwise direction in Fig. 1, with the lower end ofindexing finger 38 moving to the left over the clamp members 20, 21.

The brace arm is urged in a clockwise direction and against the end ofadjustor rod 39 by a coiled tension spring 41 fastened at one end to thebrace arm and at its other end to a side wall of the brace frame. Inpractice, the brace arm and indexing finger 38 are adjusted so that whenthe indexing finger rests against the rear edge of a cutting tooth of asaw chain, the forward edge of the tooth will be properly positioned forsharpening when the grinding wheel mount is lowered downwardly overclamp members 20, 21.

Grinding wheel mount 13 is pivoted by pivot connection 46 to an L-shapedmounting bracket 47. Bracket 47 has a horizontal leg, and the forwardend of the horizontal leg is pivotally secured to front side wall 17 bypivot 48. The bracket has a vertical leg integral with the horizontalleg which extends upwardly from the horizontal leg through an arcuateslot 49 to a point spaced above table surface 18. Bracket 47 can beswung from left to right in Fig. 1, about pivot 48 to enable thesharpening of both left and right hand cutting teeth in a saw chain.Means (not shown) are provided for fixing bracket 47 in differentadjusted positions.

Pivot connection 46 for the grinding wheel mount accommodates movementof the mount about an obliquely disposed axis. This enables the free endof the mount to move toward a saw chain in a direction inclined from avertical direction. The latter is necessary in order that a suitablybeveled cutting edge can be imparted to a cutting tooth of a saw chain.

Grinding wheel mount 13 carries at its pivoted or rear end an electricmotor 53. At the forward or nonpivoted end of the mount is a grindingwheel indicated at 54. Wheel 54 is secured by nut and washer assembly 56to a wheel arbor 57. Arbor 57 and motor 53 are drivingly connected bysuitable belt and pulleys (not shown) enclosed within casing 58.

As can be seen in Fig. 2, mounting bracket 47 has a platform portion 61integral therewith, projecting outwardly underneath mount 13. Thisportion is obscured by the mount in Fig. 1. A coiled compression spring62 interposed between platform 61 and the under side of the grindingwheel mount operates to urge the mount to a raised position. The springis held in place as by pin 63 and screw 64. Outwardly of the compressionspring on mount 13 and threaded into a tapped portion of the mount is anadjustor screw 66. The lower end of screw 66 provides an abutment whichstrikes platform 61 to limit downward movement of the grinding wheelmount. The adjustor screw is adjustable longitudinally of its length topermit adjustments in this limit position.

Referring now to Figs. 1, 3, 4, and 5, integral with the grinding wheelmount and carried on the top side thereof is a mounting hood portion 67.This hood portion has a top wall 68 and side walls 69, but openings areprovided at the two ends thereof, as seen in Fig. 3. Extending throughthe end openings of the hood portion and with one end adjacent grindingwheel 54 is a supporting arm or member 71. The other end of member 71has affixecl thereto a knob 72.

Mounting means are provided for mounting the end of arm 71 disposed awayfrom the grinding wheel. This mounting means accommodates pivotalmovement of the arm about a pivot axis which is parallel to the axis ofrotation of wheel 54, and rotary movement of the arm about an adjustmentaxis which extends at right angles to the axis of rotation of wheel 54.

Specifically, arm 71 is threaded through the smooth center bore of asleeve or support member 76 and is rotatable within this sleeve. Theaxis of this rotation is perpendicular to the rotary axis of thegrinding wheel. The arm is secured from movement longitudinally ofsleeve 76 by snap rings 77. The sleeve itself is mounted for pivotalmovement relative to mount 13 by a pair of aligned trunnions 78, 79. Thepivot axis provided by trunnions 78, 79 is substantially parallel to theaxis of rotation of the grinding wheel. The trunnions each take the formof a threaded screw member mounted in a side wall of hood portion 67 andhaving a tapered end which seats in an indent formed in the outerperiphery of the sleeve. The screw member is secured in fixed place inthe side wall mounting the same by a lock nut 81.

The inner end of supporting arm 71 has an offset portion indicated at82. Portion 82 is offset radially from the adjustment axis about whicharm 71 rotates. Thus the end of the offset portion describes a sweep onrotation of arm 71, as best illustrated in Fig. 5.

The offset portion has mounted thereon a diamond headed dresser orcutting element 83. Element 83 is screwed into an accommodating tappedbore provided in offset portion 82, and is held securely in place bylock nut 84. When nut 84 is loosened, element 84 may be turned to varythe degree of offset of the inner or cutting end of the element from theadjustment axis for arm 71.

Top cover wall 68 of hood portion 67 contains a tapped bore 86 whichreceives an elongated screw 87 having a rounded end 88 and a knob 89secured to its other end. The lower end of this screw, which constitutesan adjustable abutment means, is spaced in the path of mounting sleeve76 when the sleeve is pivoted in a clockwise direction in Fig. 3. Screw87 limits movement of the offset portion of arm 71 away from wheel 54,and thus acts firmly to hold dresser element 83 against the wheel duringdressing. Wing nut 91 is a locking nut.

Aflixed by screw 92 to the inner surface of top wall 68 is a leaf spring93. The free end of the spring engages an end of sleeve 76, and impartsa bias to the sleeve urging the sleeve into contact with screw 87.

When the apparatus is used for sharpening, grinding wheel mount 13 ispivoted downwardly with the outer periphery edge of the grinding wheelmoving against a saw tooth to sharpen it. Indexing finger 38 is adjustedso that it will properly position the saw tooth by resting against theheel of a tooth. Adjustment in the position of the indexing finger isnecessary when sharpening different sizes OfSa'iI teeth, and when thegrinding wheel is dressed and as a consequence has its diameter reduced.The latter adjustment follows from the fact that the wheel pivotsdownwardly about an oblique axis, and reducing the diameter of the wheelshifts the point of contact of the wheel with a chain longitudinallyalong members 20, 21.

When dressing a wheel, the rounded end of screw 87 is moved downwardlyto move the offset portion of arm an-gr 71 toward the periphery of thewheel, and the diamond point into engagement with the wheel periphery.

'In dressing a wheel, the motor is turned on and the wheel rotatedagainst the diamond mount. To impart a round to the edge of the wheel,arm 71 is rotated about its adjustment axis in sleeve 76. This moves thedresser element in a sweep. As long as the diamond element remains infixed position, the radius of the sweep does not change, even though arm71 is pivoted about the trunnions to take care of a reduction in thediameter of the wheel. Adjustment of the position of the dresser elementin offset portion 82 changes the radius of the sweep.

The organization is readily adjusted for dressing grinding wheels ofvaried thickness. Ordinarily the adjustment axis for arm 71 ispositioned so that it lies in a plane coinciding with a plane parallelto the opposite faces of the wheel but disposed centrally between thefaces, if a truly semicircular round between the wheel faces is desired.To take care of a thicker or thinner wheel, the adjustment axis may beshifted laterally by appropriate adjustment of trunnions 78, 79.

It is claimed and desired to secure by Lettters Patent:

1. In saw sharpening apparatus having a frame and a grinding wheel mountmounted for movement on said frame, said grinding wheel mount mounting agrinding wheel arbor that is adapted to hold a grinding wheel and isrotatable about a grinding wheel rotation axis, the improvementcomprising wheel dresser means mounted on said grinding wheel mount andcarried thereby for movement therewith, said wheel dresser meanscomprising a tubular sleeve extending substantially perpendicularly tosaid grinding Wheel rotation axis, a pair of oppositely disposed andaligned trunnions carried by said mount adjustable in position in thedirection of their length, the inner ends of said trunnions pivotallymounting said sleeve intermediate its ends for movement of the sleeveabout a pivot axis extending parallel to said grinding wheel rotationaxis, an elongated supporting arm extending through and journaled insaid sleeve for rotation about an adjustment axis perpendicular to saidgrinding wheel rotation axis and paralleling said sleeve, saidsupporting arm having an end adjacent a grinding wheel mounted on saidarbor, said end having an offset portion that is offset from saidadjustment axis in a direction radially outwardly of said grinding wheelrotation axis, a cutting element mounted on said oflset portionprojecting radially inwardly toward said grinding wheel rotation axis,and screw adjustment means carried by and adjustable on said mount andbearing on said sleeve and inhibiting pivotal movement of the sleeve ina direction where said ofiset portion of said supporting arm movesradially outwardly of said grinding wheel rotation axis.

2. The saw sharpening apparatus of claim 1 which further comprises biasmeans bearing on said sleeve and interposed between said sleeve and saidmount constructed to urge the sleeve in a direction where said olfsetportion of said supporting arm moves radially outwardly of said grindingwheel rotation axis.

3. In saw sharpening apparatus having a frame and a grinding wheel mountmounted for movement on said frame, said grinding wheel mount mounting agrinding wheel arbor that is adapted to hold a grinding Wheel and isrotatable about a grinding wheel rotation axis and also mounting coverstructure extending over and thus covering upper proportions of such agrinding wheel, the improvement comprising wheel dresser means mountedon said grinding wheel mount and carried thereby for movement therewith,said wheel dresser means 'having an elongated supporting arm with an endof the arm disposed beneath said cover structure and under and adjacentsuch a grinding wheel, a tubular sleeve journalling said supporting armwith the arm paralleling the sleeve and with the sleeve extendingsubstantially perpendicularly to said grinding wheel rotation axis, apair of oppositely disposed and aligned trunnions carried by the mountand adjustable in position in the direction of their length, the innerends of said trunnions pivotally mounting the sleeve for movement abouta pivot axis extending parallel to said grinding wheel rotation axis,said end of said supporting arm having an offset portion beneath saidcover structure offset from said grinding wheel rotation axis in adirection radially outwardly of said rotation axis, a cutting elementbeneath said cover structure mounted on said ofiset portion projectingradially inwardly toward said rotation axis, and screw adjustment meansinterposed between said grinding wheel mount and said sleeve and bearingon said sleeve and inhibiting pivotal movement of the sleeve in adirection where said oflset portion of said supporting arm movesradially outwardly of said grinding wheel rotation axis.

References Cited in the file of this patent UNITED STATES PATENTS1,182,362 Fischer May 9, 1916 1,662,079 Severson Mar. 13, 1928 2,077,727Ward Apr. 20, 1937 2,146,466 Dannecker Feb. 7, 1939 2,328,826 McQuillanSept. 7, 1941 2,374,726 Balzek May 1, 1945 2,428,786 Dahl Oct. 14, 19472,458,472 Irwin Jan. 4, 1949 2,641,089 Fouquet June 9, 1953 2,704,915Grobey Mar. 29, 1955 2,712,817 Trefz July 12, 1955 2,741,241 Teather eta1. Apr. 10, 1956 2,787,094 'French Apr. 2, 1957 2,811,873 Nielsen Nov.5, 1957 2,811,874 Rethoret Nov. 5, 1957 2,824,468 Nielsen Feb. 25, 1958

